Many quaternary ammonium compounds, such as benzethonium chloride, are known to be effective as antimicrobial agents and preservatives. However, benzethonium chloride and many other quaternary ammonium compounds are expensive. Furthermore, the efficacy of quaternary ammonium compounds generally are reduced when incorporated into anionic formulations. As a result, there is a continuing need for improved antimicrobial and preservative compositions which contain low concentrations of quaternary ammonium compounds and maintain their efficacy in anionic formulations.